Polyaniline／fractionized carbon nanotube composite was prepared with the polymerization of aniline in the FCNTs dispersed liquid．The SEM micrographs indicate that carbon nanotubes ale coated with polyaniline；the thickness of the polyaniline on carbon nanotubes is about 5～10 nm；and carbon nanotubes were dispersed well in the composite on the nanometer scale. The apparent density and the electrical conductivity of the polyaniline／fractionized carbon nanotube composite are 440 kg／m3 and 173 S／m

respectively．As compared with polyaniline

the apparent density and the conductivity of the composite increased by about 82％ and 1400％

respectively．TGA tests indicate that the composite has better thermal-stability than that of polyaniline.